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Saturday, 17 August 2013

Oracle 12c new features?

Oracle database 12c (c for cloud) a multi tenant database management system introduce so many important new capability in so many areas – database consolidation, query optimization, performance tuning, high availability, partitioning, backup and recovery (nearly 500 new features).
Pluggable Databases:
In Oracle 12c, in a pluggable database environment, we can create a single database container, and plug multiple databases into this container. All these databases then share the exact same oracle server/background processes and memory, unlike the previous versions where each database has its own background processes and shared memory. This helps in database consolidation and reduces the overhead of managing multiple desperate databases.
Consolidation is an important business strategy to reduce the cost of infrastructure and operational expense. In many production database servers, a big portion of CPU cycles go unused. By consolidating many databases into fewer database servers, both the hardware and operational staff can be more effectively utilized.
Oracle's new pluggable database feature reduces the risk of consolidation because the DBA can easily plug or unplug an existing database to or from a container database. There is no need to change any code in the application.
It is also easy to unplug a database and convert the pluggable database to a traditional database if required. In addition, you can back up and recover pluggable databases independently of the container database; you can also perform a point-in-time recovery of a pluggable database. Further, Resource Manager can be used to control resources consumed by a pluggable database.
Optimizer features:
Oracle 12c introduces a few useful SQL Optimizer features, and most of these are automatically enabled.
It is not uncommon for Optimizer to choose an inefficient execution plan due to incorrect cardinality estimates, invalid statistics, or even stale statistics. This can have dire results. A SQL statement estimated to run for a few seconds might take hours to execute if the chosen execution plan is not optimal.
  1. Identity columns which are auto incremented at the time of insertion
SQL> create table emp (emp_id number generated as identity, emp_name varchar);
SQL> create table emp (emp_id number generated as identity (start with 1 increment by 1 cache 20 noorder), emp_name varchar;
  1. Increased size limit for VARCHAR2, NVARCHAR2, and RAW datatypes to 32K (from 4K).
  2. Default on Null (A default value is inserted into the null column).
  3. Session private statistics for GTTs (Table and index statistics are held private for each session)
  4. UNDO for temporary tables can now managed in TEMP, rather than regular UNDO tablespace.
  5. For global temporary tables will not generate UNDO. Reduces contents of regular UNDO allowing better flashback operation.
  6. In oracle 12c we are able to make column invisible
SQL> create table ss (column-name column-type invisible);
SQL> alter table ss1 modify column-name invisible;
SQL> alter table ss1 modify column-name visible;
  1. In oracle 12c, No need to shutdown the database for changing Archive log mode.
  2. Datapump now allow tuning off redo for the import (only) operation.
  3. Now can create duplicate indexes using the same column, in the same order, as an existing index.
  4. The truncate command is enhanced with a CASCADE option which allows child record.
  5. Oracle 12c allows using DDL inside the SQL statements (PL/SQL inside SQL).
  6. Moving and Renaming datafile is now ONLINE, no needs to put datafile in offline.
  1. A role can now be granted to a code unit (PL/SQL Unit Security). Thus one can determine at a very fine grain, which can access a specific unit of code.
  2. We can declare PL/SQL functions in the WITH Clause of a select statement.
  3. Map Reduce can be run from PL/SQL directly in the database.
  4. We can use Booleans values in dynamic PL/SQL. Still no Booleans as database types.
  1. Introduction of Flex ASM, with this feature, database instances uses remote ASM instances. In normal conditions in a node if ASM fails the entire node will be useless, where in 12c the ability to get the extent map from remote ASM instance makes the node useful.
  2. Introduction of Flex Cluster, with light weight cluster stack, leaf node and traditional stack hub node (application layer is the typical example of leaf nodes) where they don't require any network heartbeat.
  3. Oracle ASM disk scrubbing (Checks for logical data corruptions and repair them automatically.)
  1. Accidental Drop table, Truncate Table, Wrong scripts human error recovery.
  2. RMAN TABLE Point-In-Time Recovery (combination of Data Pump and RMAN, auxiliary instance required).
  3. Recover or copy files from Standby databases.
  4. Restore & Recover individual tables from RMAN backup.
  5. Incremental recovery more faster, many of the tasks removed. You can automate the use of incremental backup to bring the standby db in sync.
  6. Import from older export files possibilities.
  1. Partitioning enhancements, Multiples partition operations in a single DDL.
  2. Online move of a partition (without DBMS_REDEFINTIION).
  3. Interval-Ref Partitions - we can create a ref partition (to relate several tables with the same partitions) as a sub-partition to the interval type.
  4. Cascade for TRUNCATE and EXCHANGE partition.
  5. Asynchronous Global Index maintenance for DROP and TRUNCATE. Command returns instantly, but index cleanup happens later.
  1. Centralized patching - We can test patches on database copies, rolling patches out centrally once testing is complete.
  2. Compression: Automated compression with heat map. Optimization can be run on live databases with no disruption. Data optimization will monitor the data usage and with policy archive old data and hot data will be compressed for faster access. Inactive data can be more aggressively compressed or archived, greatly reducing storage costs.
Data Guard:
1.      Oracle Database 12c introduces a new redo transportation method (Fast Sync redo transport) which omits the acknowledgement to primary of the transaction on the standby.
2.      Creating a new type of redo destination (“Far Sync Standby” composed only of the standby control files), the standby redo logs and some disk space for archive logs which shall be sent to the Standby database. Failover & Switchover operations are totally transparent as the "Far Sync Standby" cannot be used as the target.
3.      Data Guard Broker commands have been extended. The "validate database" command to checks whether the database is ready for role transition or not.
4.      Dataguard Broker now supports cascaded standby.
5.      Global Temporary Tables can now be used on an Active Guard standby database.
New Views/Packages in Oracle 12c Release
dba_pdbs, v$pdbs, cdb_data_files, dbms_pdb, dbms_qopatch
Using DBUA to upgrade the existing database is the simple and quickest method.
For step by step details follow the below link: Upgrade Oracle Database 11g to 12c


  1. Awesome blog.
    Posting very Useful content every time..
    Keep the blog update in future
    Thanks Once again...

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